Author

Committee Chair

Committee Member

Department

Dept. of Mechanical Engineering

College

College of Engineering and Computer Science

Publisher

University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)

Abstract

The purpose of this study was to determine if common boiler failures were mainly due to uncontrollable events or from the effects from selecting lower grade materials and processes for the components. Eighteen case studies of tubing failures were selected and examined from boilers all around the world. Twelve of the tubes failed due to excess hoop stress and six failed from some kind of cracking. Calculations were made and it was determined that seventy-five percent of the failures would not have happened if a higher grade but more expensive material had been used. It was also found that 83.3 percent of the utilities did not perform any metal treatments for the tubes that experienced cracking. Although there was no way to prove that these cracks would not have happened with some sort of stress relieving treatment, the numbers suggest this. Utilities not properly treating their metal components should carefully consider such treatment. The economizer, superheater and reheater were the boiler components selected for this study. The study was restricted to these three boiler components, although excess hoop stress and cracking failures do occur in other regions of the boiler as well. All three contained tube bend regions, but not all experienced failures in the actual bend of the tube.

Degree

M. S.; A thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Master of Science.